The present invention relates to the construction of a needle for use in dispensing fastener attachments or the like and, more particularly, to a needle assembly formed of multiple parts which is high in strength, low in cost and permits re-sharpening of the cutting edge.
Plastic fastener attachments are widely used throughout the wearing apparel and softgoods industries, as well as other industries, in order to attach labels or other items to products in a manner which prevents detachment thereof. Attachments of this type are normally made of nylon or similar high strength plastic and typically comprise a relatively thin filament connecting a T-bar end and a paddle end. Such attachments are commercially available from the Dennison Manufacturing Company of Framingham, Mass. in a number of different sizes, colors and styles.
The attachments are manufactured in clips typically containing fifty or a hundred attachments aligned in side-by-side relationship. The T-bar ends of the attachments are connected to a common runner bar. The attachments may be unconnected at their paddle ends or may be connected by various techniques to prevent tangling, as described in U.S. Pat. No. 3,733,657 issued May 22, 1973 to Gordon B. Lankton and entitled "Assembly of Attachments And Method of Manipulating The Same".
The clips of attachments are designed for use in a dispensing device known as an "attacher" or "gun". Various types of attachers or guns are known to the art and commercially available. For instance, U.S. Pat. Nos. 3,470,834; 3,759,435; U.S. Pat. No. Re. 29,310; and, U.S. Pat. No. Re. 29,819, all of which were issued to Arnold R. Bone, illustrate a number of different manually actuatable attachers or guns. In addition, a variety of different power actuated attachers or guns are also commercially available from sources such as Dennison Manufacturing Company of Framingham, Mass.
All of the attachers or guns comprise a body into which a slotted, hollow needle is mounted. The clip of attachments is inserted into the gun behind the needle. Actuation of the gun causes a plunger, aligned with the T-bar end of the first attachment in the clip, to be displaced forwardly, such that the first attachment in the clip is dispensed. Each attachment in the clip is automatically aligned with the needle in sequence prior to dispensing same.
In order to attach a tag to a garment or the like, the gun is loaded with a clip of attachments and the needle is caused to penetrate the label and the garment. The gun is then actuated, such that the T-bar end of the attachment is pushed by the plunger through the hollow needle and is situated at the rear of the garment. The needle is then withdrawn leaving the attachment with the T-bar end on one side of the garment and label, and the paddle end of the attachment on the other side of the garment and the label, such that the label is attached to the garment.
The T-bar end of each of the attachments in the clip must be severed from the clip as same is dispensed. This is achieved by severing the connection between the T-bar end and the runner bar. The attachment is severed from the runner bar by pushing the connecting part therebetween against a knife or cutting edge situated within the attacher, either on the needle itself or within the body of the attacher.
Conventional needles designed for use in these types of attachers include a shank portion which has a relatively sharp tip to permit penetration of the articles to be attached and a substantially cylindrical rear portion. The shank is hollow to permit the T-bar end of the attachment to pass therethrough and has a longitudinal slot to permit the filament of the attachment to extend therefrom as the T-bar end moves through the needle. The shank portion extends from a substantially cylindrical base having a central bore with an inner diameter equal to the inner diameter of the hollow shank. The base also has a longitudinal slot aligned with the slot in the shank. In needles which are removable from the attacher, the base is provided with means for correctly positioning the needle within the attacher and means for locking same into place.
Conventional needles of this type are produced commercially in two different ways. The base and shank may be machined from a single piece of metal. While this construction has the advantage of high strength, machining a single piece of metal into the required form is an arduous and time consuming task which results in a relatively expensive product. In order to reduce the cost of the needle, a second construction has been utilized. In this instance, the needle comprises two separate parts, a metal shank portion which is stamped from a flat sheet of metal and thereafter rolled into the desired configuration, and a plastic base part which is molded around the end of the shank portion. This construction results in a needle which is considerably less expensive than the all-metal, single-part construction. However, the two-part construction has considerably less strength than the single piece construction.
In both constructions, a knife edge is provided at the rear of the base section. In the single part construction, the knife edge, in the form of a "V"-shaped slot or the like, is machined into the rear of the base part. However, in the two part construction, the knife edge cannot be a part of the base because same is plastic and, thus, is not strong enough. Therefore, in order to provide the cutting edge in two part construction, the metal shank portion is formed with a rearwardly extending flat insert about which the base is molded. The insert extends along the entire length of the base. The "V"-shaped cutting edge is formed on the rear end of the insert and a recess is provided in the plastic of the rear of the base part adjacent the cutting edge to prevent interference of the base with the cutting operation. Thus, the cutting edge in the two-part construction is situated in the same position as the cutting edge in the single part construction. However, in the two-part construction, the cutting edge is located on the rearwardly extending metal insert which is a part of the shank portion, instead of being a part of the plastic base.
The base of the needle is locked within the body of the gun. When the gun is actuated, the plunger pushes the T-bar end of an attachment forwardly through the needle, causing the connection between the T-bar and the runner bar to be pushed against the knife edge and severed. In the single part construction, the severing of the connection between the T-bar and the running bar causes no problems because the cutting force is applied to the base which is secured to the gun.
However, in the two part construction, the forward directed cutting force is applied to the rearwardly extended insert which forms a part of the shank portion, not a part of the base. Thus, a forwardly directed force is applied to the shank portion, tending to move same relative to the stationary plastic base which is locked in the body of the gun. This causes a tendency for the metal shank portion to separate from the plastic base because of the oppositely directed forces developed therebetween.
This problem is particularly acute in attachers or guns which are power actuated because of the high magnitude of cutting force which is developed therein. It has, therefore, been found that the conventional two part construction is, in many cases, of insufficient strength to prevent separation of the shank portion from the base, resulting in a broken needle.
In addition, in both the single part and two part construction, the "V"-shaped cutting edge cannot be re-sharpened because of the inaccessibility thereof. For this reason, when the cutting edge becomes dull, the needle assembly must be discarded and replaced with a new needle assembly.
It is, therefore, a prime object of the present invention to provide a needle assembly which is as strong as the conventional single part machined needle.
It is a second object of the present invention to provide a needle assembly which is relatively inexpensive to manufacture.
It is a third object of the present invention to provide a needle assembly wherein the cutting edge is situated beyond the base to permit access thereto.
It is a fourth object of the present invention to provide a needle assembly wherein the cutting edge may be re-sharpened.
It is a further object of the present invention to provide a needle construction wherein the needle assembly includes separate metallic parts which are reliably secured together by an adhesive or the like.
It is a still further object of the present invention to provide a needle assembly wherein the needle is formed of separate metal parts, each of which is relatively inexpensive to manufacture.
In accordance with the present invention, a high strength needle assembly for dispensing fastener attachments having a sharpenable cutting blade is provided. The assembly comprises a shank part and a base part, the shank part including a tip portion and a substantially cylindrical hollow portion having an inner and an outer diameter. The base includes a central bore having first and second sections. The first section has an inner diameter substantially equal to the outer diameter of the cylindrical portion so as to permit insertion of the cylindrical portion therein. The second section has an inner diameter substantially equal to the inner diameter of the cylindrical portion. Means are provided for securing the outer surface of the cylindrical portion to the inner surface of the first section.
The cylindrical portion is provided with an end remote from the tip. This end has a substantially circular edge situated in a plane substantially perpendicular to the axis of the cylindrical portion. It is this end which is received and secured within the first section of the bore. The second section of the bore is considerably longer than the first section thereof, such that the cylindrical portion of the shank is inserted into the base only a relatively short distance.
A second aspect of the invention relates to the knife part thereof which is mounted on the base at a position thereon remote from the cylindrical portion of the needle assembly. The knife part includes an elongated body portion having a cutting edge situated on one end thereof. The other end of the body section is mounted on the base, such that the body portion extends beyond the base in a direction substantially parallel to the axis of the cylindrical portion.
The cutting edge preferably extends across the width of the outer end of the body portion and comprises a surface inclined between the faces of the body portion. The cutting edge is preferably provided with a notch therein to facilitate correct positioning of the attachment with respect to the cutting edge.
In one embodiment, means are provided for mounting the knife part to the base. The mounting means preferably comprises a recess on the base into which at least a portion of the inner end of the body portion is received. Preferably, the recess is adjacent the second section of the central base. The portion of the inner end of the knife which is received within the recess preferably comprises a protrusion which extends in a direction substantially parallel to the axis of the body portion. Means are provided for securing the protrusion within the recess. The securing means may comprise an adhesive or solder.
In a second embodiment, the knife is formed integrally with the base. Because the knife extends beyond the base, the cutting edge can be formed on the knife in a subsequent operation. The shank part can be secured to the base-knife part in the manner described above. This manufacturing method has the advantage of reduced cost, particularly when mass production techniques are utilized.
The present invention thus relates to a multiple part needle assembly wherein each part is relatively inexpensive to manufacture and the parts may be assembled in a manner which results in a high strength product. In addition, because the knife part extends beyond the base, the cutting edge is accessible, such that same may be re-sharpened.